The Status of Asthma in the United States

Introduction Asthma imposes a substantial health and economic burden on patients and their families and on the health care system. An assessment of the status of asthma in the US may lead to effective strategies to improve health and quality of life among people with asthma. The objective of our study was to assess the historical trends and current state of asthma illness and death among children and adults in the US. Methods We assessed asthma-related emergency department visits and hospitalizations among children and adults by using data from the 2010–2021 National Health Interview Survey (NHIS), the 2010–2020 Nationwide Emergency Department Sample (NEDS), the National (Nationwide) Inpatient Sample (NIS), the Healthcare Cost and Utilization Project (HCUP), and the Agency for Healthcare Research and Quality (AHRQ). Asthma death rates were calculated by using 2010–2021 National Vital Statistics System data. Results Asthma prevalence increased significantly among adults from 2013 through 2021 (P = .04 for the annual percentage change [APC] slope) and decreased among children from 2010 through 2021 (P values for slopes: 2010–2017, P = .03; 2017–2021, P = .03). Prevalence of current asthma was higher among non-Hispanic Black people (children, 12.5%; adjusted prevalence ratio [APR] = 2.19; 95% CI, 1.68–2.84 and adults, 10.6%; APR = 1.25; 95% CI, 1.09–1.43) compared with non-Hispanic White people (children, 5.7%; adults, 8.2%). Prevalence of asthma attacks and use of asthma-related health care declined among adults and children. Asthma prevalence and asthma-related emergency department visits, hospitalization, and death rates differed by select characteristics. Conclusions Although asthma attacks, ED visits, hospitalizations, and deaths have declined since 2010 among all ages, current asthma prevalence declined only among children, and significant disparities in health and health care use still exist.


Introduction
Asthma, a chronic respiratory disease, is associated with substantial illness and death (1-3), requiring ongoing medical management.The disorder is associated with a large economic cost (4) and a substantial number of missed school and workdays (5).The disorder is the focus of the Healthy People 2030 initiative to reduce asthma attacks, emergency department (ED) visits, hospitalizations, and deaths (6).Asthma disproportionately affects people from some racial and ethnic minority groups (3,7), people with low incomes (3,7), and people facing certain environmental factors (7,8).
Asthma is uncontrolled in approximately 50% of children (9) and 62% of adults (10) and results in frequent and intense episodes of symptoms (1), most commonly among children aged 0 to 4 years (59.1%) and Black people (62.9%) (9).Furthermore, ED visits, hospitalizations, and number of missed school days are higher among children with uncontrolled asthma (11).Children's ED visits for asthma declined substantially from 2006 through 2018, but disparities in these children's sociodemographic characteristics persist (3).Although asthma deaths have declined, these, too, are related to socioeconomic and demographic health disparities (3,7,12).Progress in asthma treatment has been slow, and asthma hospital admissions and deaths have declined only slightly in the past decade (13).
The Centers for Disease Control and Prevention's (CDC's) National Asthma Control Program was established in 1999 to fund asthma control in state, territorial, and municipal health departments.The program's goals are to reduce the number of deaths, hospitalizations, ED visits, school days or workdays missed, and limitations on activity due to asthma.This includes monitoring the health of people with asthma and determining health and health care disparities by analyzing data from multiple national and statebased surveys, hospital discharge records, and death vital statistics.Our objective was to describe asthma in the US by assessing prevalence of current asthma (defined as people who have ever been diagnosed with asthma by a health care professional and report still having asthma) and asthma attacks, asthma-related health care use, and asthma deaths among children and adults by sociodemographic characteristics and by trends across time.

Data sources
We used 3 data sources to calculate prevalence of current asthma and asthma attacks, asthma hospitalization rates, and asthma ED visit rates per 10,000 of the 2020 US census resident population, and to calculate the asthma death rate per million of the 2021 US census resident population: 1) the National Health Interview Survey (NHIS), 2010-2021 (14); 2) the Healthcare Cost and Utilization Project's (HCUP's) National Emergency Department Samples (NEDS) (15) and National Inpatient Sample (NIS), 2010-2020 (16); and 3) CDC Wonder (CDC Wide-Ranging Online Data for Epidemiologic Research), 2010-2021 (17).NHIS is an annual cross-sectional, in-person, household survey of noninstitutionalized US civilians that uses a geographically clustered sampling design (14).NEDS, a stratified probability sample of a set of hospital-owned EDs, is a large US all-payer database that gives national estimates of ED visits.Its data come from US hospitalowned EDs with data in the HCUP State Emergency Department Databases and the State Inpatient Databases (15).NIS data are acquired from 48 partners (47 states and the District of Columbia) and represent more than 97% of the US population.Its data include a sample of all discharges from US community hospitals, excluding rehabilitation and long-term acute care hospitals (16).

Study population
We analyzed NHIS data to calculate prevalence per 10,000 of the US census resident population for current asthma and asthma attacks among people with current asthma.We also analyzed CDC mortality data offered online from the National Vital Statistics System for asthma death rates per million US census population for 2010 through 2021 and trends across all years for 3 groups: all ages, children (aged <18 y) (hereinafter, children), and adults (aged ≥18 y) (hereinafter, adults) (17).We applied the following select characteristics to all calculations: sex (male or female, as shown in the medical record), age (0-4 y, 5-17 y, 18-34 y, 35-64 y, or ≥65 y), race (White, Black, other), ethnicity (Hispanic, non-Hispanic), and US census region (Northeast, Midwest, South, or West).The "other race" group includes Asian or Pacific Islanders, American Indians or Alaska Natives, and people of any other race (17), another single race, or multiple races.Data from the otherrace group were combined to obtain sufficient sample size for reliable estimates.

Current asthma and asthma attacks
People were classified as having current asthma if they responded yes to 2 questions: "Has a doctor or other health professional ever told you that you had asthma?" and "Do you still have asthma?"People with asthma were classified as having asthma attacks if they responded yes to 1 question: "During the past 12 months, have you had an episode of asthma or an asthma attack?"(14).Prevalence was calculated by our select characteristics.

Asthma-related emergency department visits, inpatient hospital stays, and deaths
We used NEDS to calculate ED visits per 10,000 and defined a visit as one in a which asthma is the primary diagnosis according to an ICD (International Classification of Diseases)-10-CM diagnosis code of J45 (15,18).We used NIS to calculate asthma hospitalization rates per 10,000, defined as hospital in-patient short stays (<30 days) with asthma as the primary diagnosis according to ICD 10-CM code J45 (16,18).Data from the National Vital Statistics System, accessed through CDC WONDER, were used to generate asthma death rates per million where asthma was the underlying cause of death (ICD-10 codes J45 and J46) (17).Data from 2010 through 2021 were used to calculate trends in asthma mortality rates, and estimates in 2021 were calculated by our select characteristics.Because our study was a secondary analysis of publicly available, de-identified data, it did not require CDC institutional review board approval.

Statistical analysis
We used SAS version 9.4 and SAS-callable SUDAAN 11 (Research Triangle Institute) to account for the complex sampling design of the survey data.Descriptive statistics such as stratification by our select characteristics were used to show asthma-related outcomes as they were observed in the population.We evaluated trends from 2010 to 2021 in prevalence of current asthma and having 1 or more asthma attacks during the past year among all ages, children, and adults with current asthma.In 2019, the NHIS questionnaire was redesigned (https://www.cdc.gov/nchs/nhis/2019_quest_redesign.htm),but changes did not affect our estimates.We also determined asthma indicators by our select characteristics and US census region for 2021.Sample weights were provided in the data sets for each year and were used to adjust for survey nonresponse, poststratification, and probability of selection ( 14) to get a more accurate representation of the study population.Participant response categories of don't know, refused, not ascertained, and missing values were treated as missing.Wald χ 2 tests were conducted to determine associations among demographic characteristics, US census regions, and study outcomes (ie, prevalence of current asthma and prevalence of asthma attacks among people with current asthma).
We estimated trends for 2010 through 2020 in use factor rates for asthma-related health care, including asthma ED visits and hospitalizations, per 10,000 of the US 2020 census resident population.Rates in 2020 were estimated by our select demographic characteristics.Discharge-level weights were applied from the database to produce unbiased national annual estimates from sample data (19,20).Cell sizes less than or equal to 10 using HCUP data sets were suppressed.
Trends in rates per million of asthma deaths were calculated for 2010 through 2021, and for 2021 alone, among all ages, children, and adults.Prevalence of current asthma and asthma attacks, rates of asthma health care use, and asthma death rates were also calculated.The difference between 2 population groups was assessed by using nondirectional 2-tailed z tests (at the α < 0.05 level).We used Joinpoint Regression software, version 5.0.2.0 (National Cancer Institute) to analyze trends by using log-linear regression models to determine significance trends.Joinpoint software calculates the fewest number of linear segments necessary to characterize a trend and the year(s) where 2 segments with different slopes meet.Associations between current asthma or asthma and select covariates were examined by using multivariable logistic regression models.The association between each health outcome (eg, current asthma or asthma attack) was assessed in separate models in which health outcome regressed over independent variables along with sex, age, and race and ethnicity.Adjusted prevalence ratios (APRs) were estimated by adjusting for sex, age, and race and ethnicity for all ages, children, and adults.Each of these 3 variables was only adjusted by the 2 other variables in the model (eg, age is adjusted by sex and race and ethnicity).Statistical tests used a significance level of P < .05,and 95% CIs were calculated for all estimates.

Current asthma
In 2021, 24.9 million people in the US (4.7 million children and 20.3 million adults, 7.7% of the population) had asthma (Table 1).Asthma prevalence varied over time.Current asthma among all ages and among adults showed a nonsignificant decrease in 2010-2013 (Figure 1), then increased through 2021 significantly for adults (P = .04for the slope).Among children, asthma prevalence significantly decreased from 2010 through 2021 (P =.03 for 2010-2017 trend slope, P =.03 for 2017-2021 trend slope).
Figure 1.Prevalence of current asthma and asthma attacks among all ages by year.The P value of the trend line slope is significant at P < .05.The trend line is based on estimates from the statistical model and observed prevalence estimates (estimates as is from the survey data) (dots).The trend slope is numbered (slope 1, slope 2) when there is more than one significant trend line, as in the current asthma trend lines.Data source: National Center for Health Statistics, National Health Interview Survey, 2010-2021 (14).

Asthma attacks
In 2021, about 39.4% of people with current asthma reported having 1 or more asthma attacks in the past 12 months (39.6% among adults and 38.7% among children) (Table 1).Prevalence of asthma attacks significantly decreased over time.Among people of all ages with asthma, the prevalence of attacks decreased significantly, from 51.9% in 2010 to 39.4% in 2021 (P < .001for the trend slope) (Figure 1).Among adults with asthma, attack prevalence decreased from 58.3% in 2010 to 38.7% in 2021 (P < .001for the trend slope); among children, attack prevalence decreased from 49.1% in 2010 to 39.6% in 2021 (P = .003for the trend slope).

Asthma-related emergency department visits
Approximately 1 million people in the US had an ED visit for asthma in 2020 (29.8 per 10,000 US census 2020 resident population) (Table 2).The asthma ED visit rate per 10,000 for all ages decreased significantly in 2018, from 62.7 in 2010 to 50.2 in 2018 (P = .02for the slope), but no significant changes occurred between 2018 and 2020 (P = .06for the slope) (Figure 2).Among adults, the asthma ED visit rate per 10,000 decreased significantly, from 52.3 in 2010 to 27.8 in 2020 (P <.001 for the slope).The asthma ED visit rate per 10,000 among children declined from 2010 through 2020 but was only significant between 2018 and 2020 (P = .03for the slope). .Asthma-related health care use and death rate among all ages by year.The P value of trend line slope is significant at .05.The trend line is based on estimates from the statistical model and observed prevalence estimates (estimates as is from the survey data) (dots).The trend slopes are numbered (slope 1, slope 2) when there is more than 1 significant trend line, as in the current asthma trend lines.The health care use rate is shown as the number of hospitalizations and emergency department visits per the US Census resident population for the given year.Data sources: asthma emergency department visits and hospitalizations: Healthcare Cost and Utilization Project, National (Nationwide) Inpatient Sample (16) and National (Nationwide) Emergency Department Sample (15), Agency for Healthcare Research and Quality.Asthma deaths: CDC Wonder (Wide-Ranging Online Data for Epidemiologic Research) (17).
Among children, the asthma ED visit rate per 10,000 was significantly higher for males (43.0) than for females (29.5) and for Black (89.5), other race (86.0), and Hispanic (35.2) children than for White children (14.4).

Asthma hospital inpatient stays
Nearly 100,000 people in the US were hospitalized for asthma in 2020 (2.9 per 10,000 US census 2020 resident population) (Table 2).The rate was 13.0 per 10,000 for all ages in 2010 and 10.7 per 10,000 in 2014, but no significant changes occurred between 2010 and 2014 (P = .56for the slope).The rate then decreased significantly, to 2.9 per 10,000 in 2020 (P = .001for the slope) (Figure 2).The trend in asthma hospitalizations for children and adults also declined across time.Among adults, the asthma hospitalization rate per 10,000 decreased significantly, from 12.0 in 2010 to 2.6 in 2020 (P < .001for the slope).The rate among children decreased significantly from 2010 through 2018 and further decreased through 2020 (P = .006,2010-2018; P = .005,2018-2020 for the slopes).

Asthma as the underlying cause of death
In 2021, asthma was the underlying cause of death for 3,517 (10.6 per million) people in the US (Table 3).The trend in asthma death rates among all ages (P =.88 for the slope), among adults (P = .99for the slope), and among children (P = .35for the slope) were stable from 2010 through 2021 (Figure 2).
Among children, the asthma death rate per million was significantly higher for males (2.4) than for females (1.6) and also was significantly higher for non-Hispanic Black children (7.7) than for non-Hispanic White children (1.0).

Discussion
We found that current asthma prevalence among adults increased significantly from 2013 through 2021 and decreased significantly among children from 2010 through 2021.Akinbami et al (21) found an increased trend in asthma prevalence among children from 2001 through 2008, plateauing thereafter with a possible decline starting in 2013.Improvements in asthma diagnostic testing (1,2) or changes in exposure to environmental factors linked to developing asthma might explain the trends reported in that study (22).
Another study found that prevalence of asthma attacks did not show a significant trend in either direction among adults or children in the first decade of this century (23).However, another study found a decrease in prevalence of asthma attacks among children with current asthma from 2001 through 2016 (24).We found that prevalence of asthma attacks continued to decline, showing a significant decrease in prevalence from 2010 through 2021 among both children and adults.Asthma-related ED visits and hospitalizations among children and adults decreased significantly, but the decrease in ED visits among children was only signi-ficant in later years, 2018 through 2020.Although the COVID-19 pandemic could account for asthma-related ED visits and hospitalizations in 2020, other possible reasons for the declines over the years may include improved, ongoing public health programs and use of emerging evidence-based strategies in asthma diagnosis, management, and treatment (2).Studies have also found that ED visits for asthma were lower during the COVID-19 pandemic compared with pre-pandemic years (before 2020), especially among children.This was explained by changes in the health care-seeking behaviors possibly due to the pandemic, such as exposure avoidance and fears of visiting an ED.Also, ED visits for asthma attacks triggered by COVID-19 may have been classified as COVID-19 (25).A separate trend analysis of asthma-related ED visits and hospitalization data showed significant declines among children and adults from 2010 through 2019.
Our study also found that in 2021, current asthma prevalence was lower but asthma attack prevalence was higher among children aged 0 to 4 years compared with adults aged 18 to 34 years.Past studies also found similar patterns in such children (3).Lower asthma prevalence among children aged 0 to 4 years could be because asthma in children in this age group is often underdiagnosed; its symptoms, such as wheezing and coughing, can be caused by other respiratory tract infections (eg, rhinitis, croup, pneumonia, bronchiolitis) and because of difficulties in using diagnostic lung tests (eg, spirometry) accurately in children in this age group (1).Current asthma prevalence was lower among adults aged 65 years or older than those aged 18 to 34 years.Asthma in older adults may be underdiagnosed because of underuse of diagnostic tests, challenges in application and interpretation of tests, and difficulty distinguishing asthma symptoms from similar symptoms because of other conditions (eg, congestive heart failure, emphysema, chronic bronchitis, chronic aspiration, gastroesophageal reflux disease, tracheobronchial tumors) (26,27).
Among adults, prevalence of current asthma and asthma attacks was higher for females compared with males after adjusting for age and race and ethnicity but lower for children.Asthma attacks also were not associated with sex.The reason for this sex pattern in asthma could be the effect of sex-specific hormones and pathophysiology (28).
Current asthma prevalence was higher among non-Hispanic Black children and adults and lower among Hispanic adults, after adjusting for sex and age, compared with non-Hispanic White adults.Although asthma attack prevalence did not differ by race and ethnicity, after adjusting for age and sex, prevalence was lower among non-Hispanic Black adults compared with non-Hispanic White adults.Disparities persist since our last asthma surveillance summary, which also demonstrated that prevalence remains higher among non-Hispanic Black children and adults and lower among Hispanic adults than non-Hispanic White adults (3).People with low incomes and from some racial and ethnic minority groups disproportionately experience adverse health outcomes, which may be associated with factors such as poor housing quality (7,29,30), adverse environmental exposures (7,8,12,29,30), reduced access to health care (7,31), and health care quality (7,30,31).We did not examine factors contributing to lower asthma attacks among non-Hispanic Black people.Further research is needed to identify those factors.
Further disparities were found in health care use.Children had higher rates of asthma ED visits and hospitalizations than adults, which was consistent with the findings of McDermott et al (32) and Qin et al (33).McDermott et al (32) determined that asthma was the most common reason for potentially preventable pediatric hospitalization in 2017.Despite recent advancements in medical care, an estimated 94,560 people were hospitalized and 986,453 people had ED visits for asthma in 2020, which represents a substantial burden on patients and the health care system.We also found that people of races and ethnicities other than non-Hispanic White had significantly higher rates of asthma ED visits and hospitalizations than White people.Qin et al (33) found that non-Hispanic Black and Hispanic people were more likely to have asthma-related ED visits (33).Asthma disorders and health care use are affected by socioeconomic and demographic factors that contribute to health disparities (7,31).Among children with asthma, more non-Hispanic White children used the doctor's office as their usual place for medical care than non-Hispanic Black and Hispanic children (34).Also, more Black children with insurance had cost barriers to seeing a doctor compared with White children (35).
We found that the asthma death rate was higher for female than male adults but higher among male than female children.We also found this sex pattern for current asthma and health care use.The asthma death rate was also higher among older adults, which was observed in other studies that showed asthma mortality increased with age (26).Baptist and Busse noted that management and medical care for asthma among older adults might be difficult and complicated because of comorbidities and age-related pathophysiologic changes, which can increase risk of death from asthma (26).Although some declines in asthma outcomes have been observed, that article showed continued opportunities to address health disparities.Our study's strengths are that asthma prevalence and attack data come from NHIS, which is the major and longest-running household health survey in the US (14), and from its decades worth of data to determine trends.These data include multiple major indicators (current asthma, asthma attacks, asthma-related health care use, and asthma mortality), hospital administrative data, and vital statistics data.
Our study had limitations.NHIS responses are self-reported; therefore, some misclassification and associated biases may result.Because NHIS is a cross-sectional study, a cause-and-effect relationship between outcome and independent variables cannot be inferred.In addition, asthma estimates for children are based on proxy (adult) responses and may be misclassified, although the proxy adult selected was the one most knowledgeable about the child's health.Trend results need to be interpreted considering the transition in diagnostic coding from ICD-9-CM to ICD-10-CM in October 2015 and redesign of NHIS in 2019.Additionally, the analysis time period of our study includes the COVID-19 pandemic, which began in 2020 and likely affected survey processes and asthma ED visits.

Conclusion
Although asthma attacks, asthma ED visits, asthma hospitalizations, and asthma deaths declined since 2010 among all ages, current asthma prevalence declined only among children.Significant disparities in health and health care use still exist.Our study's results can help decision makers and public health practitioners provide tailored interventions and health care initiatives to improve the health of people with asthma and reduce preventable health care use.this article.No copyrighted material, surveys, instruments, or tools were used in this article.a People who responded yes to the following questions: "Has a doctor or other health professional ever told you that you had asthma?" and "Do you still have asthma?"b Among those with current asthma, respondents were classified as having asthma attacks if they responded yes to "During the past 12 months, have you had an episode of asthma or an asthma attack?"c National Center for Health Statistics (14).d May not sum to total because of rounding and missing values.e Adjusted for age, sex, and race or ethnicity when regressing the dependent variables (ie, current asthma and asthma attacks) over each independent variable by using multivariable logistic regression models.For age, sex, and race or ethnicity variables, only adjusted for the other 2. f Significant at P <.05.Calculated by using the Wald χ 2 test of the association between outcomes and characteristics.g Non-Hispanic Asian, Non-Hispanic American Indian or Alaska Native, any other race or ethnicity, other single race, or multiple races.

Tables
(continued on next page)   h Non-Hispanic Asian, non-Hispanic American Indian/Alaska Native, non-Hispanic native Hawaiian/Pacific Islander, and non-Hispanic people of more than 1 race.i Information for Hispanic origin was missing for suppressed number of deaths.j Suppressed because the number of deaths was 9 or fewer.h Non-Hispanic Asian, non-Hispanic American Indian/Alaska Native, non-Hispanic native Hawaiian/Pacific Islander, and non-Hispanic people of more than 1 race.i Information for Hispanic origin was missing for suppressed number of deaths.j Suppressed because the number of deaths was 9 or fewer.

( 5 .
8% vs 8.2%; APR = 0.68 [95% CI, 0.59-0.80])and adults who PREVENTING CHRONIC DISEASE VOLUME 21, E53 PUBLIC HEALTH RESEARCH, PRACTICE, AND POLICY JULY 2024 The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.

Figure 2
Figure2.Asthma-related health care use and death rate among all ages by year.The P value of trend line slope is significant at .05.The trend line is based on estimates from the statistical model and observed prevalence estimates (estimates as is from the survey data) (dots).The trend slopes are numbered (slope 1, slope 2) when there is more than 1 significant trend line, as in the current asthma trend lines.The health care use rate is shown as the number of hospitalizations and emergency department visits per the US Census resident population for the given year.Data sources: asthma emergency department visits and hospitalizations: Healthcare Cost and Utilization Project, National (Nationwide) Inpatient Sample(16) and National (Nationwide) Emergency Department Sample(15), Agency for Healthcare Research and Quality.Asthma deaths: CDC Wonder (Wide-Ranging Online Data for Epidemiologic Research)(17).
VOLUME 21, E53 PUBLIC HEALTH RESEARCH, PRACTICE, AND POLICY JULY 2024 The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.
opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.

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continued on next page) PREVENTING CHRONIC DISEASE VOLUME 21, E53 PUBLIC HEALTH RESEARCH, PRACTICE, AND POLICY JULY 2024 The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.
opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.

Table 1 .
Prevalence of Current Asthma a and Asthma Attacks b Among All Ages, Children Aged 0-17 Years, and Adults Aged ≥18 Years, by Select Characteristics, Na- Abbreviation: APR: adjusted prevalence ratio; NA: not applicable; SE: standard error.

Table 1 .
Prevalence of Current Asthma a and Asthma Attacks b Among All Ages, Children Aged 0-17 Years, and Adults Aged ≥18 Years, by Select Characteristics, Na-People who responded yes to the following questions: "Has a doctor or other health professional ever told you that you had asthma?" and "Do you still have asthma?"bAmong those with current asthma, respondents were classified as having asthma attacks if they responded yes to "During the past 12 months, have you had an episode of asthma or an asthma attack?"cNational Center for Health Statistics (14).dMay not sum to total because of rounding and missing values.eAdjusted for age, sex, and race or ethnicity when regressing the dependent variables (ie, current asthma and asthma attacks) over each independent variable by using multivariable logistic regression models.For age, sex, and race or ethnicity variables, only adjusted for the other 2. f Significant at P <.05.Calculated by using the Wald χ 2 test of the association between outcomes and characteristics.gNon-Hispanic Asian, Non-Hispanic American Indian or Alaska Native, any other race or ethnicity, other single race, or multiple races.The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.
The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.a

Table 2 .
Asthma Emergency Department Visits and Hospitalization Rates a by Patient Characteristics Among All Ages, Children Aged 0-17 Years, and Adults Aged dSex categories are male and female as designated in the medical record.e Reference category.fSignificant at P < .05.P values calculated by using z test.gIncludes Asian or Pacific Islander, American Indian or Alaska Native, and other races.The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.

Table 2 .
Asthma Emergency Department Visits and Hospitalization Rates a by Patient Characteristics Among All Ages, Children Aged 0-17 Years, and Adults Aged f Abbreviation: NA, not applicable; SE: standard error.a Asthma as the primary diagnosis (ICD-10-CM Code: J45) (15,18); Nationwide Emergency Department Sample, Healthcare Cost and Utilization Project, 2010-2020 (15); and Nationwide Inpatient Sample, Healthcare Cost and Utilization Project, 2010-2020 (16).b Used sample weights provided in the data set to estimate numbers of respondents within select characteristics; may not sum to total because of rounding and missing values.c Crude rate per 10,000 US census 2020 resident population.d Sex categories are male and female as designated in the medical record.e Reference category.f Significant at P < .05.P values calculated by using z test.g Includes Asian or Pacific Islander, American Indian or Alaska Native, and other races.The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.

Table 3 .
Asthma Deaths by Select Characteristics Among All Ages, Children Aged 0-17 Years, and Adults Aged ≥18 Years -US, 2021 Centers for Disease Control and Prevention.CDC Wonder (https://wonder.cdc.gov/).b Numbers in select characteristics may not sum to total because of rounding and missing values.c Asthma as the underlying cause of death (ICD-10 codes J45-J46).(https://wonder.cdc.gov/wonder/help/ucd-expanded.html#).d Crude death rate per million, US census 2021 resident population.e Sex categories are male and female as reported in death certificate.f Significant at P < .05.P values calculated by using z test.
f Abbreviations: NA: not applicable; SE: standard error.a g Reference category.

Table 3 .
Asthma Deaths by Select Characteristics Among All Ages, Children Aged 0-17 Years, and Adults Aged ≥18 Years -US, 2021 Centers for Disease Control and Prevention.CDC Wonder (https://wonder.cdc.gov/).b Numbers in select characteristics may not sum to total because of rounding and missing values.c Asthma as the underlying cause of death (ICD-10 codes J45-J46).(https://wonder.cdc.gov/wonder/help/ucd-expanded.html#).d Crude death rate per million, US census 2021 resident population.e Sex categories are male and female as reported in death certificate.
a f Significant at P < .05.P values calculated by using z test.g Reference category.